In a gas absorption process for example in which a liquid spray contacts a gas flow a nozzle arrangement can be selected to generate a spray of liquid droplets. However nozzle arrangements generate a wide spectrum of droplet sizes. Droplets which are significantly smaller than the required mean size can enhance interfacial area but will have an increased susceptibility to gas phase entrainment.
A reduction in droplet size spectrum can be produced by imposing a uniform cyclic disturbance on to a jet of liquid. This can be achieved by applying mechanical vibration or an ultrasonic source at the jet nozzle. The disturbance causes a regular dilational wave along the jet which ultimately breaks up the jet into near uniform droplets.